1. Field of the Invention
This invention relates to a pneumatic nailing machine, more particularly to a pneumatic nailing machine having a winding air channel for exhaust.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional pneumatic nailing machine 1 as disclosed in U.S. Pat. No. 5,878,936 is shown to include a striking cylinder 11 accommodated in a main housing 10, and a piston and driver assembly 12 disposed in the striking cylinder 11 and driven to drive a nail when compressed air is supplied to the striking cylinder 11 from an upper portion 111. As shown in FIG. 1, when a trigger is pulled to move a valve stem 16 to open a passage 17, compressed air in a head valve chamber 18 is exhausted so that a head valve 13 is opened, and compressed air in an air chamber 19 bursts into the striking cylinder 11 to drive the piston and driver assembly 12 so as to strike a nail. As shown in FIG. 2, when compressed air is supplied to the head valve chamber 18 so that the head valve 13 is closed while an exhaust port 141 is opened, the compressed air in the striking cylinder 11 is discharged through the exhaust port 141 to an exhaust chamber 142, and further through throttle holes 143 into be exhausted from outflow ports 144. Meanwhile, the piston and driver assembly 12 is moved back to its initial position so as to ready for the next nailing operation.
Since the compressed air exhausted from the striking cylinder 11 flows along a substantially axial path at a very high rate, a loud noise is generated even though the throttle holes 143, through which the exhausted compressed air flows, are provided.